The present invention relates to a reference voltage generation circuit which finds applications in semiconductor integrated circuits and which includes a low power consumption start-up section for restarting a reference voltage generation section of the reference voltage generation circuit.
The reference voltage generation circuit is an important circuit having a variety of applications. A reference voltage generation circuit has been known in the art which has a reference voltage generation section for generating a reference voltage and a start-up section for restarting the reference voltage generation section. With such a configuration, even when the reference voltage generation section accidentally goes into the off state when the power is applied or due to influence of some kind caused by noise or the like, it is possible for the reference voltage generation section to restart and generate a normal reference voltage.
As long as the reference voltage generation section keeps operating normally, the start-up section stands by in the idle state, in other word the start-up section is not required to operate. However, if current continuously flows, in a steady-state manner, in the start-up section, this will introduce a problem that power consumption is greatly increased. U.S. Pat. No. 5,969,549 shows a solution to cope with the problem.
Accordingly, like the above-mentioned US patent, an object of the present invention is to lower power consumption of a reference voltage generation circuit by reducing, after the reference voltage generation section is started up, stationary current flowing in the start-up section.
In order to achieve the object, the present invention employs the following start-up section configurations for use in reference voltage generation circuits comprising a reference voltage generation section having a current mirror and configured to generate a reference voltage and a start-up section for restarting the reference voltage generation section.
A first reference voltage generation circuit of the present invention is provided with a start-up section, the start-up section including an input transistor configured to receive at its gate a voltage at a node which varies with the magnitude of a current flowing in one branch of the current mirror in the reference voltage generation section, an inverter for reversing a drain voltage of the input transistor, an output transistor for supplying a start-up current to the reference voltage generation section in order to restart the reference voltage generation section in response to an output voltage from the inverter, and a current limit transistor serially connected to the input transistor in order to receive from the reference voltage generation section a reduced gate-source voltage upon completion of restarting the reference voltage generation section for limiting a flow of current in the input transistor.
A second reference voltage generation circuit of the present invention is provided with a start-up section, the start-up section including input transistors of first and second polarities which receive at their respective gates a voltage at a node which varies with the magnitude of a current flowing in one branch of the current mirror in the reference voltage generation section and which are connected together drain to drain, and an output transistor for increasing a gate-source voltage common to two transistors together forming the current mirror in order to restart the reference voltage generation section in response to a voltage common to the drains of these input transistors of the first and second polarities.
A third reference voltage generation circuit of the present invention is provided with a start-up section, the start-up section including an input transistor configured to receive at its gate a voltage at a node which varies with the magnitude of a current flowing in one branch of the current mirror in the reference voltage generation section, an inverter for reversing a drain voltage of the input transistor, an output transistor for supplying a start-up current to the reference voltage generation section in order to restart the reference voltage generation section in response to an output voltage from the inverter, a switch serially connected to the input transistor in order to cut off a flow of current in the input transistor upon completion of restarting the reference voltage generation section, and a control transistor for receiving at its gate the same voltage as a voltage at the input transistor gate to shift an input voltage of the inverter, in order to cut off the start-up current which has been supplied from the output transistor upon completion of restarting the reference voltage generation section.
A fourth reference voltage generation circuit of the present invention is provided with a start-up section, the start-up section including an input transistor configured to receive at its gate a voltage at a node which varies with the magnitude of a current flowing in one branch of the current mirror in the reference voltage generation section, an inverter for reversing a drain voltage of the input transistor, an output transistor for supplying a start-up current to the reference voltage generation section in order to restart the reference voltage generation section in response to an output voltage from the inverter, a first switch for disconnecting the input transistor gate from the node in the reference voltage generation section upon completion of restarting the reference voltage generation section, a first control transistor for receiving at its gate the same voltage as a voltage which has been received at the input transistor gate to shift the input transistor gate voltage, in order to cut off a flow of current in the input transistor upon completion of restarting the reference voltage generation section, a second switch for disconnecting an input of the inverter from a drain of the input transistor upon completion of restarting the reference voltage generation section, and a second control transistor for receiving at its gate the same voltage as a voltage which has been received at the input transistor gate to shift an input voltage of the inverter, in order to cut off the start-up current which has been supplied from the output transistor upon completion of restarting the reference voltage generation section.
A fifth reference voltage generation circuit of the present invention is provided with a start-up section, the start-up section including a transistor for receiving at its gate a voltage at a node which varies with the magnitude of a current flowing in one branch of the current mirror in the reference voltage generation section, and for supplying a start-up current to the reference voltage generation section in order to restart the reference voltage generation section in response to the voltage. Further, a voltage lower than a power supply voltage of the reference voltage generation section is applied to a source of the transistor.